In such a device known from German Laid-open Application No. DE-OS 32 45 230 a single switching element, provided as a shift finger, is connected with the drive shaft of the step motor via a graduated collar, the graduated collar being surrounded by a fixed disk having a vernier scale. The rotating shift finger extends through a U-shaped position sensor, the device being set such that in the basic position of the two draw-down elements the leading edge of the shift finger crosses the working line of the position sensor and that in this position the zero point of the graduated collar overlies the zero point of the vernier scale. With this device it is possible to record the basic position of the draw-down elements during each shifting movement to compare it with the position of the two scales so that changes can be recorded. However, the exact recordation of the basic position of the draw-down elements depends on the permissible tolerances and the permissible play of the gear transmission between the step motor and the draw-down elements. Even though it is possible to record with this known device the opposite shifting of the two draw-down elements from the one direction to the other during lift reversal of the carriage at random places on the needle butt or butts, the known device is not capable of automatically or machine-internally determining, for example during an unforeseen outage of the machine after reactivation, which one of the draw-down elements is now in the draw-down position and which one is in the alignment position, i.e., in a position where the head of the needle is in alignment with the knock-over edge of the comb. This can only be read off from the two scales by the operator of the flat-bed knitting machine.